/*
        
        File:			decrypt.cpp
        Program:		decrypt
	Author:			Michael Rossberg
				mick@binaervarianz.de
	Description:		KisMAC is a wireless stumbler for MacOS X.
                
        This file is part of KisMAC.

    KisMAC is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License, version 2,
    as published by the Free Software Foundation;

    KisMAC is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with KisMAC; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#include <pcap.h>
#include <IOKit/IOTypes.h>
#include <iostream.h>
#include "80211b.h"
#include "RC4.h"

typedef struct _header {
    /* 802.11 Header Info (Little Endian) */
    UInt16 frameControl;
    UInt8  duration;
    UInt8  id;
    UInt8  address1[6];
    UInt8  address2[6];
    UInt8  address3[6];
    UInt16 sequenceControl;
    UInt8  data[100];
} __attribute__((packed)) header;

#define KEY "\x62\x6c\x61\x62\x6c"
#define KEYSIZE 5

typedef unsigned long int UNS_32_BITS;
typedef void (*keyfunction)(unsigned char *);

#define UPDC32(octet,crc) (crc_32_tab[((crc) ^ (octet)) & 0xff] ^ ((crc) >> 8))

static UNS_32_BITS crc_32_tab[] = { /* CRC polynomial 0xedb88320 */
0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c,
0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106,
0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
};


unsigned long doFCS(unsigned char* buf, int len) {
    int i;
    unsigned long crc=0xffffffff;
    for(i=0;i<len;i++) {
        crc=UPDC32(buf[i],crc);
    }
    return(crc);
}

//make this support WDS systems

int main(int argc, const char *argv[]) {
    char err[PCAP_ERRBUF_SIZE];
    const u_char *b;
    struct pcap_pkthdr h;
    pcap_t *aPCapIN;
    pcap_dumper_t* pw;
    UInt32 s;
    int ret;
    header* f;
    UInt8 x[3000], key[16] = {0};
    RC4 rc;
    UInt8* data;
    int framelen;
                            
    if (argc!=3) {
        cerr << "usage: " << argv[0] << " input output\n";
        return -1;
    } 
    
    aPCapIN=pcap_open_offline(argv[1],err);
    if (aPCapIN==NULL) {
        cerr << "Could not open dump file:" << err << "\n";
        return -2;
    }

    pw=pcap_dump_open(aPCapIN,argv[2]);
    if (aPCapIN==NULL) {
        cerr << "Could not open output file.\n";
        ret=-3;
        goto error1;
    }
    
    setupIdentity();		//initialized the RC4 sboxes
    memcpy(key+3,KEY,KEYSIZE);
    
    b=pcap_next(aPCapIN,&h);
    while(b) {
        memcpy(x,b,h.caplen);
        f=(header*)x;
        if (((f->frameControl&IEEE80211_TYPE_MASK)==IEEE80211_TYPE_DATA)&&(h.caplen>=32)) {
            if (f->frameControl & IEEE80211_DIR_MASK == IEEE80211_DIR_DSTODS) {
                data = f->data + 4;
                framelen = h.caplen - 4;
            } else {
                data = f->data;
                framelen = h.caplen;
            }
            
            memcpy(key, data, 3);
            RC4InitWithKey(&rc, key, KEYSIZE+3); 
            for(s = 4;s < (framelen-24);s++) 
                data[s-4]= data[s] ^ step(&rc);

            if (doFCS(data, framelen-28) == 0xdebb20e3) {
                f->frameControl &= ~IEEE80211_WEP;
                h.caplen -= 8;
                h.len -= 8;
                pcap_dump((u_char*)pw,&h,x);
                cout << "decrypted packet\n";
            } else cout << "FCS failed.\n";
        }
        b=pcap_next(aPCapIN,&h);
    }    

    ret=0;


    pcap_dump_close(pw);
error1:
    pcap_close(aPCapIN);

    return ret;
}